One of the most capable lines in high end dampers is the JRZ RS Line. It really can do it all. From daily driving to lap records, it has the ability baked into the design. We will note that almost every manufacturer says this; the point of this post is to explain why and then break down the options. If you are looking for what JRZ can do for you, then this should help you make some choices.
First, let’s talk about why the JRZ RS Line can do what it does from a physical standpoint. Everything starts with compression damping for JRZ. The founder of JRZ, creator of this damper design, and the underlying damping philosophy – Jan Zuijdijk – started everything from there. His main goal was to settle the vibrations of the unsprung mass (wheel, tire, upright/knuckle/etc) with the shaft displacement. Essentially, this was how twin tube dampers worked at the time of concept, and this is where the remote reservoir concept came in. The remote reservoir added a lot more volume for the gas charge, separated the gas and oil volume, as well as giving more space to incorporate the compression valve. Piston rod diameter was made at 22mm to give sufficient area to give high volumes of flow to the valve enabling it to respond to small movements.
Compression control was achieved by a simple yet very effective mechanism, the blow off valve. This was – and still is- a really precise washer. Turned on a lathe and then surface ground on the acting side, it is pushed closed by springs whose preload is adjusted with the compression knobs. It will hold a certain amount of pressure dictated by the spring load and then open up, allowing oil to flow freely past, while maintaining the cracking/opening pressure. Practically, this means a lot of low speed control can be built into the damper without it being rough on bumps. Low speed is was controls the chassis and bumps are what unsettles the unsprung mass, jostles the tire, and vibrates the chassis around. JRZs (and many others now) compression valve does an excellent job at controlling low velocity low frequency oil flow (chassis movement) and opening up for the bigger stuff (bumps).
What this means for you is that tuned to the right ratios, the chassis is solid and stable while the bumps are handled without upsetting anything. To supplement this, Jan designed a free flowing piston (known internally as the 80/60) which is linear in action. The faster the damper moves, the more resistance this piston provides. This allows as much rebound control as necessary to be built in, while adding a little extra compression force at very high speed events where needed. Again, whether you are on the track or street, the bumps are handled while the chassis is set solid. This is almost always a positive outcome. When it isn’t we’re here to make that adjustment for you.
Now, which package is the best for you?
Two main groups make up the RS Line: canister and non canister. Deciding between these two starts with budget and rules. Canister/remote reservoir options cost more but work better. Some sanctioning bodies do not allow remote reservoirs (at best a poorly informed method of cost control but I digress) and there we can get creative with motorsport options as well.
Canister/Remote reservoir options are the RS Pro and RS Pro 3. These are the original JRZ Motorsport design. Both designs feature the blow off valve, 80/60 piston, and 22mm shaft. We have a wide library of valvings, settings, spring rates, and configurations available. Either damper can be delivered to your door ready to bolt in and work perfectly for your needs. Their versatile design coupled with our collective knowledge & experience make positive outcomes easy.
The difference between the RS Pro and RS Pro 3 is the introduction of low speed bleed adjustment. By allowing some flow to go around the blow off valve, e can change the velocity of suspension travel that it opens. Primarily, this changes chassis control & balance, which is a major element of tuning for performance and handling. A second, and very relevant effect especially for street cars, is that this bleed allows free movement on the street. Many of the bumps on the street aren’t very tall and can end up energizing only the tire or soaking up compression valve preload. This can create a “wavy” feeling in the suspension. The RS Pro 3 eliminates that. While adding another adjustment may seem daunting remember these can be left in the middle and work perfectly well. Also, we’re always here to help.
Your non canister options are the RS One and RS Two. These are a full circle development for JRZ, given that the original designs were meant to improve on twin tube designs. Essentially, the RS Two is a compact RS Pro. From the blow off valve, to the piston design, and ratios of damping offered, performance is very similar. The twin tube design made to achieve this do allow the oil and gas to mix, however. This was a trade off in allowing the performance philosophy of JRZ to shine through, notably compression control, which is largely absent from many (but not all) non-remote reservoir damper designs. What this means practically is that over long runs the gas will dissolve into the oil, softening the effect of the hydraulic resistance. Typically this happens about 15 to 25 min into a track session so for many, a non factor. When it does apply, we recommend increasing adjustments an extra click or two which typically brings performance back to baseline.
Reducing cost and complexity from the RS Two brings us to the RS One. This is the same exact damper with the blow off valve replaced by a shim stack. By stacking shims in place of the blow off valve, we can do a few important things. First we can get a very accurate blow off force with each damper, making repeatably easy. Building on that, the shim stack can be easily changed so in situations where compression needs to be adjusted or matched to an adjustable test set, the RS One can get it done. Another benefit of the shim stack is a smooth response, contributing to the RS Ones superior street ride. If you want something solid, fun. and easy, the RS One is a fantastic choice.
Thanks for reading, if you have more questions, please reach out. We are happy to answer. Check back soon as we have more articles being written every week.
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Learn about the JRZ Motorsports line here. You can also learn about the JRZ AT Pro line here.